Using nothing but a smartphone attached to a stick, construction workers made an astonishing find after accidentally cutting a hole in the floor of London's Garden Museum: a crypt containing 30 coffins.

After closer inspection of the site that was once the church of St. Mary-at-Lambeth, it's now believed that five Archbishops of Canterbury were buried there, including Frederick Cornwallis, John Moore, Matthew Hutton, Thomas Tenison and Richard Bancroft, who oversaw the publication of the English translation of the Bible for the Church of England.

“It was the crown — it's the mitre of an archbishop, glowing in the dark,” the director of the museum exclaimed.

(The Garden Museum via Vimeo)

Calling it one of the most incredible things he'd ever seen, former chair of the Heritage Lottery Fund Wesley Kerr told the BBC, "To know that possibly the person that commissioned the King James Bible is buried here is the most incredible discovery and greatly adds to the texture of this project."

The Garden Museum, formerly the medieval and Victorian church of St Mary-at-Lambeth

(Google Maps Street View)

"We thought there was no crypt because it's so close to the Thames that it would have been flooded," said Garden Museum Director Christopher Woodward.

"The Victorians cleared hundreds, if not thousands, of coffins out [of the grounds] to make this new building — nobody told us to expect to find anything."

Set to reopen in May after closed for 18 months and getting over $9 million worth of renovations, the Garden Museum will feature a glass panel so that visitors may get a glimpse of the undisturbed coffins below.